The method of producing glass mat by the "wet-process" is well-known in the art. Glass fibers are placed in a water solution to produce a slurry. This slurry is mechanically agitated to disperse the glass fibers uniformly throughout the slurry. The solids content of this slurry is quite low, on the order of less than 1 percent. The slurry is applied to a moving screen, where, by means of a vacuum, a majority of the water is removed resulting in a continuous web of glass fibers. After formation of the web, a binder substance is applied to assist in bonding the fibers together. The bonded web is then passes through a dryer for evaporating any remaining water and for curing the binder.
Typically, type E glass is used in the production of glass fibrous mats. However, it would be advantageous to use type A glass since the A glass has a lower melting point than E glass, and thus less energy is consumed to melt A glass. Also, certain compositions of A glass contain constituents which are less expensive than the corresponding constituents in E glass. For Example, A glass typically contains alloys which are less expensive; such as less expensive alloys can be used since A glass has a lower melting point of E glass. However, there are several drawbacks to using A glass to produce glass mat using the "wet-process" method. A glass has a relatively high alkali content. During the "wetprocess" method of forming glass mat the alkali constituents have a tendency to leach from the glass. The leaching of the alkali constituents to the surface of the glass fiber causes the fibers to adhere or clump together, thus causing poor dispersion of fibers in the slurry.
There has now been invented an improved method for producing glass fibrous mat using relatively high alkali glass. This invention is directed to that improvement.